<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
</head>
<body>
    <div id="app">
        商品名称：{{name}}
        <input type="button" value="-1" v-on:click="methodSub">
        数量：{{count}}
        <input type="button" value="+1" @click="methodAdd">
        <input type="text" name="ss" @input="updateValue('自定义参数',$event)" /><br>
        总价：{{totalprice}}
    </div>
    <script>
        let vm = new Vue({
            el:"#app",
            data() {
                return {
                    count:0,
                    price:20,
                    totalprice:0,
                    name:""
                }
            },
            methods: {
                methodSub(e) {
                    console.log(e);
                    this.count--;
                    this.totalprice=this.price*this.count;
                },
                methodAdd(e){
                    console.log(e);
                    this.count++;
                    this.totalprice=this.price*this.count;
                },
                updateValue(e){
                    console.log(e);
                    this.name = e;
                }
            },
        });
    </script>
</body>
</html>